1. Field of the Invention
The present invention relates to an apparatus and method for controlling a voltage gain in an ultra wideband receiving apparatus; and, more particularly, to an apparatus and method for controlling a voltage gain in an ultra wideband receiving apparatus, which can facilitate packet detection and improve reception performance in an initial packet detection section by controlling a voltage gain in an initial frame transmission section by using an Automatic Gain Control (AGC) value obtained in a previous frame transmission section and stored in a register.
This work was supported by the Information Technology (IT) research and development program of the Korean Ministry of Information and Communication (MIC) and the Korean Institute for Information Technology Advancement (IITA) [2006-S-071-01, “Development of UWB Solution for High Speed Multimedia Transmission”].
2. Description of Related Art
FIG. 1 is a view showing the structure of a transmission frame used in a general ultra wideband system.
As shown in FIG. 1, the transmission frame used in the ultra wideband system contains a Physical Layer Convergence Protocol (PLCP) preamble 100, a PLCP header 110 and a PLCP Service Data Unit (PSDU) 120.
An ultra wideband receiving apparatus performs packet detection 101, AGC 102, initial timing acquisition, channel estimation, initial frequency error estimation/compensation, and equalizer convergence by using the PLCP preamble 100.
The PLCP header 110 contains a Physical layer (PHY) header, a Medium Access Control (MAC) header, and a Header Check Sequence (HCS). An MAC transmitter generates the PHY header and the MAC header, and transfers them to a baseband modem transmitter. Then, the baseband modem transmitter generates the HCS from the received PHY header and MAC header, and transfers the same to a radio frequency (RF) transmitter.
The ultra wideband receiving apparatus restores a reception signal from the PSDU by continuously operating reception modules such as a rake receiver, a tracking module, an equalizer and a viterbi decoder by using the information acquired from the PLCP preamble 100. Thereafter, the restored reception signal is transferred to an MAC receiver.
FIG. 2 is a block diagram illustrating the configuration of an ultra wideband transmitting/receiving apparatus to which the present invention is applied.
Referring to FIG. 2, the ultra wideband transmitting apparatus to which the present invention is applied includes an MAC transmitter 200, a baseband modem transmitter 210, a digital-to-analog converter (DAC) 220, an RF transmitter 230, a transmission antenna 240 and a reception antenna 250. In addition, the ultra wideband receiving apparatus to which the present invention is applied includes a reception antenna 250, an RF receiver 260, an analog-to-digital converter (ADC) 270, a baseband modem receiver 280 and an MAC receiver 290.
Hereinafter, the ultra wideband transmitting apparatus will be explained in detail. First, the MAC transmitter 200 transfers a transmission signal 211 to the baseband modem transmitter 210. The baseband modem transmitter 210 generates a transmission frame 221 from the received transmission signal 211 according to an ultra wideband transmission standard, and transfers it to the DAC 220. The DAC 220 converts the digital signal, i.e., transmission frame, 221 transferred from the baseband modem transmitter 210 into an analog signal 231, and transfers the same to the RF transmitter 230. Then, the RF transmitter 230 converts the received baseband signal, i.e., analog signal, 231 into an RF signal 241, and outputs it to the transmission antenna 240 through a band pass filter.
An RF signal 241 passing through an ultra wideband channel 245 is received at the RF receiver 260 through the reception antenna 250. Here, the RF signal 251 contains various noises 247 of the ultra wideband channel 245. The RF receiver 260 converts the RF signal 251 into a baseband signal 261, and delivers it to the ADC 270. The ADC 270 converts the received analog signal, i.e., baseband signal, 261 into a digital signal 271, and transfers the same to the baseband modem receiver 280. Then, the baseband modem receiver 280 detects a reception signal 281 from the received digital signal, i.e., transmission frame 271, and transfers it to the MAC receiver 290.
In general, the conventional ultra wideband receiving apparatus judges whether or not a packet is transmitted by using the PLCP preamble 100. This judgment section is called a packet detection section 101. At this time, if the magnitude of the digital signal inputted to the baseband modem receiver 280 through the ADC 270 is processed to be suitable for a real reception signal, the baseband modem receiver 280 can more precisely judge the presence/absence of a frame.
Next, if it is judged that the packet is being currently transmitted in the packet detection section 101, the conventional ultra wideband receiving apparatus controls a voltage gain amplifier of the RF receiver 260 by driving an automatic gain controller of the baseband modem receiver 280 with respect to the corresponding packet. By this control of the voltage gain amplifier, the RF receiver 260 controls a voltage gain of an RF signal, and transfers it to the ADC 270.
At this time, the conventional ultra wideband receiving apparatus uses an initially set reference value as a voltage gain amplifier control signal of the RF receiver 260 in the packet detection section 101, regardless of an actually received input signal. Accordingly, the magnitude of a signal inputted to the baseband modem receiver 280 through the ADC 270 in the packet detection section 101 is very different from that of a signal inputted after the automatic gain controller which is driven in an AGC section 102. As described above, in the conventional ultra wideband receiving apparatus, a reception signal 261 with a voltage gain controlled by the predetermined reference value is inputted to the baseband modem receiver 280 without passing through the automatic gain controller, thereby lowering reception performance.